Charge forming device



Oct. 18, 1932. F. E. AsELTlNE CHARGE FORMING DEVICE Filed Dec. 7. 1928 s r im s N .Mue m L M. m 3 u ma @m Mg Q M m5 wlw i uw? N`\\ \W\ *mx A o* MW n www 3 QM, QW ww! L J B i w o QNQ m, N\\ A a NN N .patented `Get. 18, 1932 UNiTED s*'rAg'rls's,l

PATENT oFFici-:l-,v

l Fnsi) E. AsELTInE, oEnAYfroN, oHidAssIGNoitBY MEsNE ASSIGNMENTS, 'To DELoo PEonUc'rs coRPonATroN, oii DAYTON, oHio', Aconromirion or vDELAWARE CHARGE romaine DEVICE y Application led December 7, 1,928. Serial.-Noi 324,359.

This invention relates toa charge forming device for internal combustion engines and more particularly to the typekof charge forming device comprising al plurality ofprimary fuel mixing chambers, one for each engine intake port, which cooperate respectively with a plurality of secondary mixing chambers, each of which is locatedadjacent an engine intake port and Vreceives a primary mixture l10 of fuel and air yfrom a pipe lconnected with A one of the primary mixingchambers, and receivesvair, when required, through one branch of an air manifold, which supplies airto all the secondary mixing chambers.' The fuel is conveyed to the primary` mixingchambers through .a single fuel duct leading froma common float'bowl. v s y An example of a charge forming device of this character is disclosed in the application f@ y of liVilford H. Teeter, Serial No. 221,872, filed September 22, 1927, which matured to Paten 1,819,495 granted Aug. 1,8, 1931.

In earlier forms of charge forming devices of the character referred to, asfor instance *fzs that disclosed in the above mentioned application of lWilford H.l Teetercertain diii'iculties have been met under certain operating conditions in the formation of a primary mixture of proper proportions because i of the "o formation of eddy currents within the pri- E mary mixture passages adjacent the fuel nozzles, which disturb the suction conditions maintained :in such passa-ges so that the flow of fuel from the jets is not always what it 'if-5 should be to form a mixture of the desired proportions. Itis the principalobjectiofkthe present invention to improve the construction of the mixture passages so as to eliminate the formation of eddy currents therein and'to A o prevent suoli turbulence as will eifectthe flow of fuel from the nozzles.

This object is accomplished accordingtor the present invention by the provision of a plurality of primary mixing chambers, each "Q5 of which is an entity entirely separate from its associated mixture passage.H A passage connects each primary vmixture passage with i the main air chamber andthe primary mixture passage is enlarged at the point where f 30 it communicates with the above mentioned 'of a multicylinder engine, each of, which serves two adjacent cylinders, asV disclosed passag e `The primary mixing chambers communicate with the associated mixture passagesgby means of tubes projecting therefrom in to I the fenlargedV ,portions of the primary mixture passages above referred to andthese tubes are concentric withV the mixture passages. The fuel yjets communicate withithe primary mixing' chambers and the suction at said jets is due not only to the suction in the mixture passages which is communicatedV to the mixing chambers, but also to the aspirating action at the ends ofthe aboveV mentioned tubes created by air passing all around the tubes. Whatever turbulence may exist in themixture flowing through the mixture pasv i.: sages; is prevented by the above described structure from being `communicated to the primary mixing chambers adjacentthe fuel jets yand fwhatever variation in suction is ent invention is clearly shown. l^lnthedrawing:

FigQl is a verticalv section through the car-Kw buretor and the middle of lthat branch of the* manifold. Y

Fig. 2is a transverse vertical section on the line 2 2 of Fig. 1.

Fig. 3is a detailed sectionv on the line 3 3V 'ofFig.1. 1 i" fj'Fig.' 4 is a detailed'view of the vprimary throttle valve. j

The device illustrated comprises a main air manifold 'indicated in its entirety' by the reference numeralv l() and having threek outlet branches, the middle branch 12beiiig. shown herein. Each of 'these branches communicates with one of the intake ports 14 in the copending applicationabove referredy to.y 'i

Each of thefmanifold branches is provided with an attaching flange 16 forsecuring the uit manifold to the engine block in the usual manner and the flange 18, to which the carburetor unit may be attached, is provided adjacent the manifold inlet. The carburetor unit comprisesa main housingV 20, having an attaching flange 22, adapted to be secured by screws 24, to the fiange 18. An

held tight against a shoulder 36, formed on an annular flange projecting downwardly from the casting 28,` by means of avscrew 40, screwed into a depending portion of the casting 30, as indicated in Fig. 1.

-Fuel is conductedfrom the main source of supply to the fuel bowl` and the flow Vis p controlled by .a float 42 inthe Yusual manner to maintain a constant level of fuel in the bowl. To convey fuel from the bowl to a plurality of ,primaryV mixing chambers 44, hereinafter more fully described, a vertical fuel passage 46 is provided in the casting 80. The passage 46 communicates with an enlarged chamber 48, which is connected by means of a horizontal passage 50 to ra chamber 52, which communicates with three pairs of calibrated low and high speed Vfuel jets 54 and 56 respectively, each of these pairs fof jets beingadapted to admit fuel to one of the mixing chambers 44 previously referred to. y e Y Fuel is lifted from the fuel bowl to the primary mixture passages by the suction therein. vWhen the throttle is moved toward closed position, to reduce the engine speed, this suction may be reduced suiiiciently to allow the fuel column between the fuel jets kand the bowl 34 to drop enough to temporaril starve the engine unless means are pro- Vvic ed to prevent such action. Such means comprises a check valve 58 positioned in the .enlarged chamber 48. This valve is normally lifted above au annular rib 60 projecting upwardly fromthe floor of-said chamber by the engine suction, but on reduction of this suction, immediately seats onk saidrib preventing downward flow of fuel in the pasy sage 46. All of the fuely is admitted to the passage 46 at low speeds through a fixed orifice 62, but at high speeds additional fuel is admitted through anorilice 64, which communicates with the passage 46 by means of the horizontal passage 66. The orifice 64 `is controlled vby a valve 68, operated in the manner set forth in the 'above mentioned application.

Primary mixing chambers 44, above referred to, are bored horizontally in the casting 28, parallel to each other and relatively close together, as indicated in the drawing. Air is admitted to each of these mixing chambers'through air inlet bushings 70, one of which is screwed into the outer end of each mixing chamber. Immediately posterior to each of the air inlet bushings a small VenturiV tube 72'is received in an enlargement 74, formed in each mixing chamber. Each of these Venturi tubes is provided with two external ribs 76 arranged circumferentially of the tube and fitting tightly in the enlargement 74. These ribs form between them a fuel channel 78 with which the low speed jet communicates and the series of orifices 80 are provided in the wall of the Venturi tube to connect the interior of such tube with the above mentioned fuel channel.

The Venturi tube 72 is reduced in size at its inner end and is spaced from the wall of the primary mixing chamber, as indicated by reference numeral 7 3 in Fig. 1. This space 7 3 constitutes a dead air space in which the suction is substantially the same as that maintained in the mixing chamber, while the suction within the Venturi tube is greater than the mixingV chamber suction because of the Venturi action. Each of the main fuel jets terminates iush with the wall of the mixing chamber at a point opposite the reduced inner end of the Venturi tube. With the above described arrangement, the greater suction of the Venturi tube is effective to cause a flow of fuel from the jet 54 at all engine speeds, while the lesser suction of the 'mixing chamber, which is effective to cause a flow of fuel from the jet 56 is inedective to draw fuel therefrom until some predetermined engine speed is reached, as is fully described in applicants copending applica- Ation Serial No. 288,684, in which the above described structure is fully disclosed. The primary mixture formed in the prfmary mixing chamber 44 fiows from said chambers through tubes 90 of somewhat less diameter than the primary mixing chambers and which are secured in a block 92, which is seated in a recess-94,Y of a shape corresponding to that of the block 92, and which is formed in the casting 28. The tubes 90 1project into enlarged chambers 96 in said lock 92'which surround the tubes 90 and vwhich communicate with the main air chainber hereinafter described, bymeans of passages 98,'there being three of the chambers 96 and three passages 98 communicating therewith.A The chambers 96 are tapered at their posteriorv ends, as indicated by the reference numeral 100, and communicate with three passages 102, formed in the casting 28, as indicated in Fig. 1. The enlarged chambers 96 and the passages 102 form what may be termed for convenience the primary mixpreviously mentioned.

turel passages. Flow of-'primary mixture through the passages 102 is controlled by a primary throttle rvalve 104, which extends across all of said passages and is provided conveying the primary mixture to the scc-V ondary mixing chambers, hereinafter more fully described. The passage 102, which is adapted to supply primary mixture to the middle branch of the manifold, communi- Cates with a pipe 110, which is secured in the branch 12 of the manifold, as shown in Fig. 1, and the conduits communicating with the other passages 102 are of the same construction, as shovvn in the above mentioned copending application Serial No. 221,37 2.

All of the air entering the carburetors, except that which flows through. the lbushing 70, is admitted through the air horn 26, the flow being controlled Lby an air valve 112, normally held against the seat 114 by a spring 116, received bet-Ween the valve and a flange 118, projecting from a sleeve 120,*'slidably mounted on a fixed sleeve 122,*Which is screwed into the casting 28, and which serves as a guide for the air valve stem 124, as fully disclosed in the copending application'above referred to.

When it is desired to choke the carburetor to start the engine, theV flange 118 is adapted to be lifted by means of an arm 126, through the medium of operating vconnections not shown herein, until the upper end of the sleeve 120 engages the air valve to hold it against its seat.k starting fuel from the fuel nozzles to the engine intake ports is kadmitted through the air inlet bushings 70. n

The valve 112 admits air to a main air chamber 130 from which chamber the air flows to the primary mixture passages through the orificesV 98, previously referred to, and to the secondary mixing chambers through an air passage 132, controlled by a manually operable throttle valve. 134, secured to a shaft 136, pivoted in the housing 20. rI`he passage 132 communicates With the inlet of the vmain air manifold 10, as indicated in Fig. 1, and the throttle 134 is adapted to be operated concurrently With the throttle 104 by means of operating connections which constitute no part ofthe present in ventioii, but Whichare fully shown in the above copending' application. of either or both throttle valves, the suction in the air chamber is increased and the air valve is opened against the pressure of its spring to admit additional air and increase Suilicient air 'to carry thev On opening y the quantity of mixture supplied to the engine. The opening of the valve must be retarded temporarily, however, to prevent admission of sufficient air to lean the mixture,

and to prevent fluttering of the air valve.l

To effect these results a dash pot comprising acylinder 140 forming a part of the casting 30, and a piston 142, secured to the valve i stem 124, by means of a nut 144 or any other desirable Way, is provided. The construction of the dash pot is immaterial in so far as the present invention is concerned, and any conventional form of dash pot may be employed with equally advantageous results. Y

As previously stated, the throttle opeiated mechanism forms no part of this invention, and it is not disclosed therein, but in order to facilitate understanding of the device as a Whole, the mode4 of operationl of the two throttle valves Will be briefly described.

During operation at all engine speeds, below that correspondingto approximately the vehicular speed of 20 miles per hour onv the level, it is desired that the primary mixture passages supply all of the combustible mixture and at speeds higher it 'is desirable to admit air to the secondary mixing chambers through the passage 132. To secure this result, the tWo throttles 104 and 132 aro pro vided Withl a common operating mechanism so constructed that the primary throttle 104 is given a certain predetermined movement before the throttle 134 begins to open, and after said throttle 134 begins to open'both throttles will move together to their Wide open positions.

There are three secondary mixing chambers of identical construction, each of which comprises a Venturi tube 150 secured in an outlet branch of the manifold in such position that its point of greatest suction is immediately adjacent the outlet end of theprimary mixture conduit associated with that particular manifold branch, as shown infFig. 1. Each Venturi tube is provided With an external circumferential rib 152, which, when the device is assembled, is clamped between the shoulders 154 and 156 formed on the manilfold and on the engine block respectively.

These Venturi tubes cause the air passing thev end of the primary mixture delivery conduits to move at relatively high velocity under all operating conditions in order to create in each conduit a relatively high suction at all times when the engine is operating.

TheL construction above described, With the exception of the arrangement of the tubes 90,

the chambers 96 and passages 98 in the block i 92` is disclosed inthe two applications above referred to, parts of each of the vdevices dis- Wilford H.T'eeter, the air entering the pri- I `nozzles project, there being no restriction in the mixture passages or other means to prevent such an action. yThe iiow of air through the primary mixture passages adjacent .the

nozzles, as well as elsewhere, is, therefore, irregular, resulting lin irregularities in engine suction effective on the nozzles, and 1rregularity in fuel fiow and mixture proportions. Moreover, in the other application referred to herein in which no air passages are provided between 'the primary mixture passage and the air chamber, the velocity of flow through said primary mixture passages is such as to create further difficulties in 'mixture proportioning.` it is desirable to admit air to the primary mixture passages from the main air chamber to reduce the velocity of iiow past the jets, as it has been found difficult to prevent the formation of too rich a mixture when the velocity at the jets is suiicient to create a velocity head, but when the air is admitted to the primaryy mixture passages through an 'openinv' such as disclosed in the above application Serial No. 221,3?v 2, admission ef such air may produce the diiiiculties above discussed, making it difficult to maintain an even suction-at the fuel jets on any given throttle position. The arrangement of the passages 98 and 96 in the block 92 is designed to reduce the formation ofeddy currents and turbulence in the primary mixture pa sages, and to prevent the effect of such disturba -ces in flow being communicated to the fuel nozzles as much as possible. The air enters through the passages 9S, which are substantially perpendicular to the axes of the primary mixture passages and then flows through the passages 96, which are coaxial with the passages 102 and form part of the primary mixture passages. The tapered surface 94, provided at the posterior end of thepassage 96, straightens out the air flowing through the passage 96 as it enters the passage 102, the surface 94 providing in 'effect a stream line surface. Moreover, since the cross sectional areas of the passages 96 and 9S are somewhat greater than the area ofthe passage 102, the suction produced in such passages is more nearly equal to the suction inthe air chamber than that .in the passages 102, and the velocity of flow through such passages is necessarily less them in the smaller passages 102. Since the tubes project into the passage V,96 and are coaxial therewith, there is a substantially evenV flow of air on all sides of said tubes and at the ends of said tubes in a direction generally parallel to the axes of the tubes. This produce an aspirating effect at the end of said tubes and the suctions at the end of said tubes will be substantially equal on all sides thereof..

By causing the air passing the ends of the tubes 90 to flow in a substantially straight line, the formation of eddy currents and the resulting irregularity in suction at the end of said tubes is very considerablyy reduced and by provision of the tubes 90 of less cross sectional area than the mixing chambers 44:, such variations in suction as may occur in the passages 96 are not communicated in full to the chambers 44. In' other words, the restricted tubes 90 prevent the full effect of variations in suc-tion posterior to said tubes being transmitted to points anterior thereto, thus producing a more even suction in th mixing chamber than has been heretofore possible and a more regular flow of fuel from the ets.

' The provision of tubes 90 of smaller cross sectional area than the mixing chambers il produces a further advantage by reducing the velocity of flow through said mixing chambers. lVith such a construction of fuel jets as is disclosed herein, it is desired to maintain a suction on the high speed jet which, is a static suction and not influenced by the velocity of air flowing through the mixing chamber, as is fully set forth in the above mentioned application Serial No. 288,684.

It should be obvious that by reduction in the velocity of flow through the mixing chambers, the tendency to produce a suction in said chambers which is either wholly or in part determined by the velocity of flow therethrough is correspondingly reduced.

Vhilethe form of embodiment of the present invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

Vhatis claimed is as follows:

1. A charge forming device for internal combustion engines comprising a mixture passage, a mixing chamber adapted to supply a mixture of fuel and air to said passage, means for supplying fuel and air to said mixing chamber, and a restricted connection between the mixing chamber and the mixture passage, said connection comprising a tube of smaller cross sectional area than the mixing chamber and projecting into said mixture passage spaced from the wall thereof and having its axis substantially parallel with the axis thereof. f

V2. A charge forming device for internal combustion engines comprising a mixture passage, a mixing chamber adapted to supply a mixture of fuel and air to said passage,

means for supplying fuel and air to said mixing chamber, and a restricted connection between the mixing chamber and the mixture air flowing past the end of these tubes will passage, said connection comprising a tube projecting into the mixture passage, said tube being coaxial with the mixture passage and spaced from the wall thereof.

3. A charge forming device for internal combustion engines comprising a mixture passage, a mixing chamber adapted te supply a.

mixture of fuel and air to said passage, means for supplying fuel and air to said mixing chamber, an auxiliary air inlet admitting auxiliary air to the mixture passage, and a restricted connection between the mixing chamber and the mixture passage adjacent the auxiliary air inlet, said connection comprising a tube projecting into the mixture passage, said tube being coaxial with said mixture passage and spaced from the wall thereof to permit the auxiliary air entering the mixture passage to' iiow around the tube. Y

4. A charge forming device for internal.l

. charge end of the tube whereby an aspirating action is effected.

5. A charge forming device for internal combustion engines comprising a mixture passage, a mixing chamber Vadapted to supply a mixture of fuel and air to said passage, a plurality of fuel inlets for supplying fuel thereto, means for causing a flow of air pastv one of said jets at high velocity to create a velocity head at said jet to effect a flow therefrom, and means for preventing a flow of air through the mixing chamber at sufficient velocity to create a velocity head at the other of said jets during engine operation under any operating condition.

6. A charge forming device comprisinga plurality of primary mixing chambers, a plurality of primary mixture passages into which said mixing chambers are adapted to deliver a primary fuel mixture, a plurality of secondary mixing-chambers into which said primary mixture passages deliver, means for supplying fuel and air to said primary chambers, a -main air chamber adapted' to supply air to Aall of said primary mixture passages and secondary air chambers, a plurality of passages, each of which is adapted to connect one of said mixture passages with the air chamber, means in each of said mixture passages to minimize the formation of eddy currents and turbulence inthe mixture passages by the admission of air thereto, and means associated with each of said primary mixing chambers to prevent the effect of any eddy currents and turbulence in the mixture passage being communicated thereto.

7 A charge forming device for internal combustion engines comprising a mixture passage,'a. mixing chamber adapted to supply a mixture of fuel and air to said passage, a pluralityof fuel inlets for supplying fuel thereto, means for causing a flow of air past one of said jets at high velocity to crea-te a velocity head at said jet to effect aflow therefrom, means for shielding one of said jets from the incoming air to prevent an aspirating action at said jet, and means for preventing a iow of air through the mixing' chamber at sufficient velocity to create a velocitv head at said last named jet under any operatiing conditions, said means comprising a restricted outlet connecting the mixing-` chamber with said mixture passage.

In testimony whereof I hereto aix my signature. p v FRED E. ASELTINE. 

